MRI distortion and stereotactic neurosurgery using the Cosman-Roberts-Wells and Leksell frames

Area of Science:

• Neurosurgery
• Medical Imaging
• Biomedical Engineering

Background:

• Geometrically distorted magnetic resonance (MR) images can compromise the accuracy of stereotactic intracranial neurosurgical procedures.
• Precise target localization is critical for the success of these interventions.

Purpose of the Study:

• To evaluate the impact of stereotactic frame systems on geometric accuracy in MR imaging for neurosurgery.
• To identify sources of distortion and assess methods for correction.

Main Methods:

• Implementation of a multi-scan imaging protocol with reversed frequency-encoded readout gradient on a 1.5-tesla GE Signa system.
• Testing with a phantom and Cosman-Roberts-Wells (CRW) frame to measure geometric shifts.
• Comparison of MR image-based localization with intraoperative ventriculography in patients.

Main Results:

• Significant geometric shifts (up to 10 mm) were observed with the CRW frame, primarily due to its magnetic properties.
• Correction of distortions improved target coordinate determination.
• Images acquired with an MRI-compatible Leksell stereotactic frame exhibited minimal geometric distortion.

Conclusions:

• The magnetic properties of stereotactic frames critically influence the geometric accuracy of MR images used in neurosurgery.
• Proper design and manufacture of stereotactic frames, particularly MRI-compatible ones, are essential for accurate frame-based stereotactic neurosurgery.
• The accuracy of stereotactic frame systems is empirically testable.